The invention is directed to a swash plate pivot bearing, in particular, for a hydraulic axial piston machine with a variable throughput volume, in which roller-bearing segments are arranged between a hollow-cylindrical bearing surface for a swash plate in a housing and a cylindrical bearing surface on the swash plate. These roller-bearing segments are held in arcuate cages, wherein means for controlling the cage are provided, which prevent the cage holding the roller body from sliding out of its most favorable position in the pivot bearing.
Axial piston hydraulic units with variable displacement or variable flow rate use a pivoting swash plate, in order to control the displacement or flow rate of the piston within a rotating cylinder block. A typical type of pivoting swash plate is the cradle-type swash plate, which is held in a housing so that it can pivot by via arcuate roller-bearing segments. For this known construction, a tracking device, which prevents the cage holding the roller body from sliding out of its range of motion set for it, namely from its most favorable position in the pivot bearing, is allocated to the swash plate pivot bearing. If there is no tracking device, such slipping is possible, because the roller bodies perform not only rolling motions, but also sliding motions due to fast pivoting movements and/or vibrations and/or the inertia of the roller-bearing segment, which lead to shifts in the position of the roller-bearing segment. This produces an unfavorable position of the bearing segment or segments towards the load direction.
To drive the roller-bearing segments so that they respond to the movement of the swash plate and so that they are moved by the desired degree, in order to guarantee correct roller contact and loading for distribution, the following tracking devices are known:
For example, in DE 25 21 312 B1, a swash plate pivot bearing is described, which is distinguished in that on each cage, an elastic rod extending approximately radial to the curvature of the arcuate cage can shift in the radial direction and is hinged so that it can pivot and the rod is supported so that it can pivot with one end fixed in position at one point of the housing and can pivot with its other end on the swash plate and is arranged so that it can move in its longitudinal direction. Other similar tracking devices are described in DE 28 26 928 A1 and in EP 0 182 354 B1.
DE 16 53 617 C appears to be somewhat more closely connected to the invention. There, a tracking device is described for a cage of a swash plate pivot bearing, wherein parts thereof are provided with positive-locking elements. For this purpose, the segment-like cage is provided with a rotating pinion, which meshes with bent teeth segments that are fixed with screws, on one side, in the housing and, on the other side, to the sides of the swash plate.
All of these tracking devices have the common disadvantages that they have a complicated construction, they are made from many components, and they require additional installation space. Another reason is that the connections have either projections extending perpendicular and into corresponding boreholes in the swash plate and in the housing or openings that slide on pivot pins, which extend perpendicular from the swash plate and the housing. In both cases, the connections are installed after the swash plate was installed, which requires an access opening in the side of the housing. The opening must then be covered by a removable cover with a type of seal between the housing and the cover. Providing an access opening, the cover, and the seal further increases such a pivot bearing.
Indeed, roller bodies provided with positive-locking elements are also already known, as U.S. Pat. No. 3,938,865 shows. The means-effect relationships described there, however, are completely different in comparison with the invention. The cylindrical or conical rollers shown in this document have teeth at opposing ends for preventing slip. It is a long-known problem in roller-bearing technology that the friction fit between the inner ring, roller bodies, and outer ring is lost in the unloaded zone. In this zone, the roller bearings reduce their rotational speed. When entering the load zone, they must then be accelerated again abruptly, so that the normal roll-off process can proceed. This causes wear in the roller bodies in the load or acceleration zone, in particular, at a certain load and rotational speed ratio.